| 摘要 |
PURPOSE: An optical disc unit and an optical disc reproducing method are provided to control the focusing position of light beam precisely on an optical disc having multiple recording mark layers. CONSTITUTION: An optical disc unit comprises a play light source which radiates reproduction beam not converging on a single spot in an optical disc(100) having a recording layer(101) including one or more mark layers(Y), an objective lens(18) which changes the radiation angle of the reproduction beam and projects parallel beam to include a target position in a target mark layer, a reproduction beam detecting section having a detection zone, and a reproduction processing section detecting the presence of recording mark in the target position. |
